Display apparatus

ABSTRACT

A display apparatus including an image generator, a projection lens set, a depth detecting module detecting the position of user, and a control unit is provided, wherein the control unit is electrically connected to the image generator, the projection lens set and the depth detecting module. An image displayed by the image generator is projected through the projection lens set and generates a floating real image between the projection lens set and the user. Each beam forming the floating real image has a light-cone angle θ. The image generator and the projection lens adjust the position of the floating real image according to the position of user. The size of the floating real image is L, the distance between two eyes of the user is W, the distance between the user and the floating real image is D, and the light-cone angle θ satisfies the formula of 
     
       
         
           
             θ 
             ≥ 
             
               
                 tan 
                 
                   - 
                   1 
                 
               
                
               
                 ( 
                 
                   
                     L 
                     + 
                     W 
                   
                   D 
                 
                 )

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefits of U.S. provisionalapplication Ser. No. 61/506,155, filed on Jul. 10, 2011. In addition,this application claims the priority benefit of Taiwan applicationserial no. 100149642, filed on Dec. 29, 2012. The entirety of each ofthe above-mentioned patent applications is hereby incorporated byreference herein and made a part of this specification.

BACKGROUND

1. Technical Field

The technical field relates to a display apparatus, and moreparticularly to a display apparatus having a floating real image.

2. Related Art

In recent years, the continuous advancement of display technologies haveresulted in the increasing demands on display quality of displays, suchas image resolution, color saturation, and so on. Besides the trendtowards high image resolution and color saturation, displays capable ofdisplaying stereoscopic images have been developed to satisfy the user'sdesire for viewing realistic images.

Conventional stereoscopic displays are limited by the software andhardware restrictions of the planar display or projection techniquesadopted, in which a user is required to wear a special pair ofstereoscopic glasses when viewing the stereoscopic images. Even withauto-stereoscopic techniques, a severe crosstalk issue exists whichcauses bodily discomfort for the viewer when viewing the stereoscopicimages with crosstalk. Therefore, manufacturers are looking forward to astereoscopic display which provides a comfortable viewing experience forthe user.

Moreover, in many touch control interfaces that are currently available,the corresponding messages and feedback actions are received by usingfingers to touch the touch control panels. However, this operating modeis conducive to germ contamination since the touch control interfaceshave been touched for extended periods of time. In order to preventgerms from contaminating the user, manufacturers are looking forward toa touch control virtual interface with floating images in space whichenables user interaction. Therefore, manufacturers are earnestlystriving to overcome the restriction of distance variation between theuser and the stereoscopic display.

SUMMARY

The disclosure provides a display apparatus capable of generating afloating real image and adjusting the position and size of the floatingreal image according to the user position.

The disclosure provides a display apparatus suitable for viewing by auser. The display apparatus includes at least an image generator, aprojection lens set, a depth detecting module, and a control unit. Theimage generator displays at least an image. The projection lens set islocated between the image generator and the user, and the imageprojected by the projection lens set generates a floating real imagebetween the projection lens set and the user. Each beam forming thefloating real image has a light-cone angle θ, each beam has a chief rayand a plurality of marginal rays, each marginal ray and thecorresponding chief ray has an included angle α, and the light-coneangle θ=2α. Moreover, the control unit is electrically connected to theimage generator, the projection lens set, and the depth detectingmodule. The depth detecting module detects the position of the user, andthe image generator and the projection lens set adjusts the position ofthe floating real image according to the position of the user. The sizeof the floating real image is L, the distance between two eyes of theuser is W, the distance between the user and the floating real image isD, and the light-cone angle θ satisfies a formula:

$\theta \geq {{\tan^{- 1}\left( \frac{L + W}{D} \right)}.}$

In summary, by the emitted beam from the projection lens set satisfyinga specific relationship, the display apparatus in the disclosure cangenerate a floating real image between the projection lens set and theuser. Moreover, by using the depth detecting module to detect the userposition, and the control unit electrically connected to the imagegenerator, the projection lens set, and the depth detecting module, theimage generator and the projection lens set can adjust the position ofthe floating real image according to the user position. In someembodiments, the floating real image is an auto-stereoscopic image, or astereoscopic floating real image viewable by a pair of stereoscopicglasses. Accordingly, the display apparatus in the disclosure canprovide the user a realistic interactive experience that is true tolife.

Several exemplary embodiments accompanied with figures are described indetail below to further describe the disclosure in details.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings constituting a part of this specification areincorporated herein to provide a further understanding of thedisclosure. Here, the drawings illustrate embodiments of the disclosureand, together with the description, serve to explain the principles ofthe disclosure.

FIG. 1 is a schematic view illustrating a display apparatus according toan embodiment of the disclosure.

FIG. 2 is a schematic view illustrating a projection lens set in adisplay apparatus according to an embodiment of the disclosure.

FIG. 3 is a schematic view illustrating a projection lens set in adisplay apparatus according to an embodiment of the disclosure.

FIG. 4 is a schematic view illustrating a projection lens set in adisplay apparatus according to an embodiment of the disclosure.

FIG. 5 is a schematic view illustrating a projection lens set in adisplay apparatus according to an embodiment of the disclosure.

FIGS. 6A-6C are schematic views illustrating a light path of a floatingreal image generated after an image is projected by a projection lensset in a display apparatus according to an embodiment of the disclosure.

FIGS. 7A and 7B are schematic views illustrating an adjustment of therelative positions of the image generator and the projection lens setaccording to an embodiment of the disclosure.

FIG. 7C is a schematic view illustrating an adjustment of a floatingreal image location according to a user position in a display apparatusaccording to an embodiment of the disclosure.

FIGS. 8A and 8B are respective schematic views illustrating a userwearing a pair of stereoscopic glasses to view the display apparatushaving the projection lens set depicted in FIG. 2.

FIGS. 9A and 9B are respective schematic views illustrating a userwearing a pair of stereoscopic glasses to view the display apparatushaving the projection lens set depicted in FIG. 4.

FIGS. 10A and 10B are schematic views illustrating a display apparatususing auto-stereoscopic 3D display panels to replace conventional 2Dplanar display panels according to an embodiment of the disclosure.

FIG. 11 is a schematic view illustrating a framework of a displayapparatus according to an embodiment of the disclosure.

DESCRIPTION OF EMBODIMENTS

FIG. 1 is a schematic view illustrating a display apparatus according toan embodiment of the disclosure. Referring to FIG. 1, a displayapparatus 200 is suitable for viewing by a user 10. The displayapparatus 200 includes at least an image generator 210, a projectionlens set 220, a depth detecting module 240, and a control unit 250. Theimage generator 210 displays at least an image 212, for example a firstimage generator 210A displays an first image 212A, and a second imagegenerator 210B displays an second image 212B. The image generator 210is, for example, a display panel, a light emitting device, or an objectbeing illuminated by light. The projection lens set 220 is locatedbetween the image generator 210 and the user 10. The image 212 projectedby the projection lens set 220 generates a floating real image 260between the projection lens set 220 and the user 10.

Moreover, the control unit 250 is electrically connected to the imagegenerator 210, the projection lens set 220, and the depth detectingmodule 240. The depth detecting module 240 detects the position of theuser 10, and the image generator 210 and the projection lens set 220 mayadjust the position of the floating real image 260 according to theposition of the user 10. Specifically, each beam 262 forming thefloating real image 260 has a light-cone angle θ, in which each beam 262has a chief ray 262C and a plurality of marginal rays 262M, eachmarginal ray 262M and the corresponding chief ray 262C has an includedangle α, and the light-cone angle θ=2α. In particular, the size (i.e.maximum size) of the floating real image 260 is L, the distance betweentwo eyes of the user 10 is W, the distance between the user 10 and thefloating real image 260 is D, and the light-cone angle θ satisfies afollowing formula:

$\theta \geq {\tan^{- 1}\left( \frac{L + W}{D} \right)}$

Since each beam 262 forming the floating real image 260 has thelight-cone angle θ satisfying the above formula, therefore, after theimage 212 displayed by the image generator 210 is transmitted throughthe projection lens set 220, the user 10 can view a floating real image260. For example, when the image generator 210 is an apple illuminatedby light, by adjusting the light-cone angle θ of the beam 262 projectedafter passing through the projection lens set 220 to satisfy a followingformula:

${\theta \geq {\tan^{- 1}\left( \frac{L + W}{D} \right)}},$

the user 10 can view a floating real image 260 of the apple between theprojection lens set 220 and the user 10. It should be noted that, whenthe beam 262 projected from the projection lens set 220 satisfies theabove formula, a viewing angle of the floating real image 260 viewed bythe user 10 is no longer restricted within a specific small range. Thatis to say, the floating real image 260 can be viewed at a large viewingangle. The large viewing angle referred to herein means that, even ifthe user 10 moves left or right by 11 cm, the user 10 can still view theentire undistorted floating real image 260. In other words, the displayapparatus 200 of the present embodiment can provide floating real imagesat a viewing angle of 34 degrees (+/−17 degrees) for the user 10.

Moreover, as shown in FIG. 1, the projection lens set 220 of the presentembodiment includes a beam combiner 222, a first lens set 224A, a secondlens set 224B, and a third lens set 224C. The first image 212A displayedby the first image generator 210A is transmitted through the projectionlens set 220 and generates a first floating real image 260 aA, and thesecond image 212B displayed by the second image generator 210B istransmitted through the projection lens set 220 and generates a secondfloating real image 260 aB. The first floating real image 260 aA and thesecond floating real image 260 aB of the present embodiment are locatedon different planes, for example, and a stereoscopic imaging effect canbe directly generated. As to other embodiments of the projection lensset 220 and the generation of the stereoscopic imaging effect, furtherelaboration thereof is provided later in the disclosure.

It should be noted that, by utilizing the control unit 250 and the depthdetecting module 240, the display apparatus 200 in the disclosure canprovide user-friendly operation and realistic interaction for the user10. Specifically, the control unit 250 controls the movement of theimage generator 210 according to the position of the user 10 detected bythe depth detecting module 240, so as to adjust the relative positionsof the image generator 210 and the projection lens set 220, the positionof the floating real image 260, and the size of the floating real image260.

The depth detecting module 240 detects the position of the user 10, andthe depth detecting module 240 may detect the position of the body ofthe user 10, or the position of the fingers of the user 10 touching thefloating real image 260. Regarding the implementation of the depthdetecting module 240, reference may be directed to the co-pending U.S.Patent Application No. 61475648, Apparatus and Method for Depth ImageCapturing, and the related mechanisms are described later in thedisclosure. In brief, the depth detecting module 240 feeds the detectedposition information of the user 10 back to the control unit 250. Afterthe control unit 250 performs simple operations, the control unit 250can calculate the position of the user 10, the position of the floatingreal image 260, and the required size of the floating real image 260.Accordingly, the image generator 210 and/or the projection lens set 220are shifted by corresponding distances to achieve the needed imagevariation effects.

Description of an embodiment of the projection lens set in the displayapparatus of the disclosure is provided hereafter, with other elementsomitted.

FIGS. 2 and 3 are schematic views illustrating a projection lens set andan image generator in a display apparatus according to an embodiment ofthe disclosure. In FIGS. 2 and 3, a quantity of the image generator 210is one, and the image generator 210 has a single light path design.Referring to FIG. 2, the projection lens set 220 of the presentembodiment includes two lens sets 224 located on a projection path ofthe image 212. Each of the lens sets 224 is formed by at least one lens,and the lens may be an aspherical lens, a spherical lens, or a Fresnellens. Moreover, a total focal length of each of the lens sets 224 is apositive value. In other words, referring to FIGS. 1 and 2, the controlunit 250 of the present embodiment controls the relative positions ofthe two lens sets 224 in the projection lens set 220 relative to theimage generator 210 according to the position information of the user 10detected by the depth detecting module 240, so as to adjust the positionand the size of the floating real image 260.

On the other hand, referring to FIGS. 1 and 3, the projection lens set220 of the present embodiment includes a reflector 220R, a first lensset 224A, and a second lens set 224B, in which the reflector 220R is atotal reflector mirror, for example. The reflector 220R is located onthe projection path of the image 212. The first lens set 224A is locatedon the projection path of the image 212 and located between the imagegenerator 210 and the reflector 220R. The second lens set 224B islocated on the projection path of the image 212 and located between thereflector 220R and the user 10. In other words, in the presentembodiment, according to the position information of the user 10detected by the depth detecting module 240, the control unit 250controls the relative positions between the first lens set 224A, thesecond lens set 224B, or the reflector 220R, or the control unit 250adjusts the relative position of the projection lens set 220 relative tothe image generator 210. Accordingly, the control unit 250 controls theposition and the size of the floating real image 260. Furtherelaboration on the position adjustment methods and the relationshipbetween the imaging position and the size are provided later in thedisclosure.

FIG. 4 is a schematic view illustrating a projection lens set in adisplay apparatus according to an embodiment of the disclosure. In FIG.4, the quantity of the image generator 210 is two, and the imagegenerator 210 has a dual light path design. As shown in FIGS. 1 and 4,in the present embodiment, the image generator 210 includes the firstimage generator 210A and the second image generator 210B. The firstimage generator 210A displays the first image 212A, and the second imagegenerator 210B displays the second image 212B. Moreover, the projectionlens set 220 includes the beam combiner 222, the first lens set 224A,the second lens set 224B, and the third lens set 224C, in which the beamcombiner 222 may be a half mirror, or a dichroic mirror selectivelyreflecting and transmitting different wavelengths of light. The beamcombiner 222 is located on a projection path of the first image 212A andthe second image 212B, and the beam combiner 222 reflects the firstimage 212A and transmits the second image 212B. The first lens set 224Ais located on the projection path of the first image 212A and locatedbetween the first image generator 210A and the beam combiner 222. Thesecond lens set 224B is located on the projection path of the secondimage 212B and located between the second image generator 210B and thebeam combiner 222. The third lens set 224C is located on the projectionpath of the first image 212A and the second image 212B, and locatedbetween the beam combiner 222 and the user 10. In other words, referringto FIGS. 1 and 4, according to the position information of the user 10detected by the depth detecting module 240, the control unit 250 adjuststhe relative positions between the first lens set 224A, the second lensset 224B, the third lens set 224C, or the beam combiner 222, or thecontrol unit 250 adjusts the relative position of the projection lensset 220 relative to each image generator 210. Accordingly, the controlunit 250 controls the position and the size of the floating real image260. Further elaboration on the position adjustment methods and therelationship between the imaging position and the size are providedlater in the disclosure.

FIG. 5 is a schematic view illustrating a projection lens set in adisplay apparatus according to an embodiment of the disclosure. In FIG.5, the quantity of the image generator 210 is three, and the imagegenerator 210 has a three light path design. As shown in FIG. 5, in thepresent embodiment, the image generator 210 includes the first imagegenerator 210A, the second image generator 210B, and a third imagegenerator 210C. The first image generator 210A displays the first image212A, the second image generator 210B displays the second image 212B,and the third image generator 210C displays a third image 212C.Moreover, the projection lens set 220 includes a first beam combiner222A, a second beam combiner 222B, the first lens set 224A, the secondlens set 224B, the third lens set 224C, and a fourth lens set 224D. Thefirst beam combiner 222A is located on a projection path of the firstimage 212A, the second image 212B, and the third image 212C. The firstbeam combiner 222A reflects the first image 212A and the third image212C and transmits the second image 212B. The second beam combiner 222Bis located on a projection path of the first image 212A and the thirdimage 212C, and the second beam combiner 222B reflects the third image212C and transmits the first image 212A. The first lens set 224A islocated on the projection path of the first image 212A and the thirdimage 212C, and located between the second beam combiner 222B and thefirst beam combiner 222A. The second lens set 224B is located on aprojection path of the second image 212B and located between the secondimage generator 210B and the first beam combiner 222A. The third lensset 224C is located on the projection path of the first image 212A, thesecond image 212B, and the third image 212C, and located between thefirst beam combiner 222A and the user 10. The fourth lens set 224D islocated on a projection path of the third image 212C, and locatedbetween the third image generator 210C and the second beam combiner222B. In other words, referring to FIGS. 1 and 5, according to theposition information of the user 10 detected by the depth detectingmodule 240, the control unit 250 controls the relative positions betweenthe first lens set 224A, the second lens set 224B, the third lens set224C, the fourth lens set 224D, the first beam combiner 222A, or thesecond beam combiner 222B, or the control unit 250 adjusts the relativeposition of the projection lens set 220 relative to each imagegenerator. Accordingly, the control unit 250 controls the position andthe size of the floating real image 260.

FIGS. 6A-6C are included to further elaborate on the relationshipsbetween the relative positions of the image generator and the projectionlens set, and the position and the size of the floating real image.

FIGS. 6A-6C are schematic views illustrating a light path of a floatingreal image generated after an image is projected by a projection lensset in a display apparatus according to an embodiment of the disclosure.The display apparatus is, for example, a display apparatus having theprojection lens set depicted in FIG. 5. In other words, the presentembodiment adopts the three light path design, and the lens sets in theprojection lens set 220 can allow two common channels of light paths.One of the light paths is described hereafter as an illustrativeexample. In the example, a focal distance of the lens set in theprojection lens set 220 closer to the image generator 210 is f1, and afocal distance of the lens set in the projection lens set 220 closer tothe floating real image 260 is f2, in which f1 and f2 are respectively26.2 cm and 30.3 cm, for example. When the relative positions of eachelement in the projection lens set 220 are fixed, an imaging locationand a magnifying power of the floating real image 260 can be controlledby adjusting an object distance D1 between the image generator 210 andthe projection lens set 220.

To be specific, the object distance D1 between the image generator 210to the projection lens set 220 in FIG. 6A is shorter than the objectdistance D1 in FIG. 6B. For example, the object distance D1 in FIG. 6Ais shorter than the lens focal length f1, and the object distance D1 inFIG. 6B is equal to the lens focal length f1. Accordingly, an imagedistance D2 generated in FIG. 6A between the floating real image 260 andthe projection lens set 220 is longer than the image distance D2 in FIG.6B. Moreover, the magnifying power generated in FIG. 6A of the floatingreal image 260 relative to the image 212 is greater than the magnifyingpower generated in FIG. 6B of the floating real image 260 relative tothe image 212. On the other hand, the object distance D1 between theimage generator 210 to the projection lens set 220 in FIG. 6C is longerthan the object distance D1 in FIG. 6B. Accordingly, the image distanceD2 generated in FIG. 6C between the floating real image 260 and theprojection lens set 220 is shorter than the image distance D2 in FIG.6B. Moreover, the magnifying power generated in FIG. 6C of the floatingreal image 260 relative to the image 212 is less than the magnifyingpower generated in FIG. 6B of the floating real image 260 relative tothe image 212.

For example, in FIG. 6B, the object distance D1 is 27.4 cm, the imagedistance D2 is 20 cm, and the magnifying power is 1. In other words, thesize of the floating real image 260 in FIG. 6B is equal to the size ofthe image 212. In FIG. 6A, the object distance D1 is 17 cm, the imagedistance D2 is 34.2 cm, and the magnifying power is 1.36. That is tosay, the size of the floating real image 260 in FIG. 6A is larger thanthe size of the image 212. In FIG. 6C, the object distance is 60 cm, theimage distance D2 is 2.17 cm, and the magnifying power is 0.54. In otherwords, the size of the floating real image 260 in FIG. 6C is smallerthan the size of the image 212. By adopting the imaging relationshipsdescribed above in conjunction with a plurality of light path patterns(described later), the image 212 displayed by the image generator 210can be respectively imaged at any position between the user 10 and theprojection lens set 220. Moreover, the size of the floating real image260 can be varied according to a requirement.

Tables 1 and 2 list the optical design parameters in a projection lensset of a display apparatus according to an embodiment of the disclosure.According to the embodiment described in Tables 1 and 2, the floatingreal image 260 can be imaged 20 cm in front of the projection lens set220, and the user 10 can be located 50 cm in front of the floating realimage 260. This design allows viewing at a large viewing angle, suchthat even if the user 10 moves left or right by 11 cm, the entireundistorted floating real image 260 can be viewed. In other words, thedisplay apparatus 200 of the present embodiment can provide floatingreal images at a viewing angle of 34 degrees for the user 10.

TABLE 1 Surface Information Aperture Element Curvature Shape Thicknessor Size (X) Shape (Y) Number Surface (mm) (Y) Spacing (mm) (mm) (mm)Material Display INF FLT 272 Panel Lens 1 1 312.411 A-1 95 211.470 CIRPMMA Lens 1 2 −198.914 A-2 140 234.232 CIR 239.679 CIR Lens 2 1 INF. FLT3 402.122 CIR BK7 Schott Lens 2 2 INF. FLT 160 400.335 CIR 263.546 Lens3 1 577.436 A-3 64.3273 287.813 CIR PMMA Lens 3 2 −302.590 A-4 1 280 CIRLens 4 1 723.445 A-5 47.072 280 CIR PMMA Lens 4 2 −1998.841 A-6 202.6616303.379 CIR 296.246 Image INT FLT 125.915

Table 2 are design parameters of the aspheric lenses in Table 1, inwhich the parameters of the aspheric constants are follow the formulabelow, and the corresponding parameters are listed in Table 2:

$Z = {\frac{({CURV})Y^{2}}{1 + \sqrt{1 - {\left( {1 + K} \right)({CURV})^{2}Y^{2}}}} + {(A)Y^{4}} + {(B)Y^{6}} + {(C)Y^{8}} + {(D)Y^{10}}}$

TABLE 2 Aspheric Curvature K A B A-1 0.00320091 0.000000 −2.27084E−080.00000E+00 A-2 −0.00502730 0.000000 1.97629E−08 0.00000E+00 A-30.00173179 0.000000 −5.80782E−08 0.00000E+00 A-4 −0.00330480 0.0000004.60121E−10 0.00000E+00 A-5 0.00138228 0.000000 4.53787E−08 0.00000E+00A-6 −0.00050029 0.000000 −3.34722E−09 0.00000E+00

FIGS. 7A and 7B are included to elaborate on the adjustment of therelative positions of the image generator and the projection lens set.

FIGS. 7A and 7B are schematic views illustrating an adjustment of therelative positions of the image generator and the projection lens setaccording to an embodiment of the disclosure. These schematicrelationship views describe how the final image location of the floatingreal image 260 can be varied by changing the object distance D1 betweenthe image generator 210 to the projection lens set 220. Referring toFIG. 7A, in some applications, an actuator 270 can be used to move theimage generator 210, such that the image generator 210 shifts along anaxis relative to the projection lens set 220 to adjust the distancebetween the image generator 210 and the projection lens set 220, andthereby changing the image ratio or the image location of the floatingreal image 260. The single axial movement may be, for example, along amovement direction M1, a movement direction M2, or a rotation directionM3, although the disclosure is not limited thereto. As shown in FIG. 7A,when the position of the image generator 210 moves from a position P1 toa position P2, the corresponding image location of the floating realimage 260 is also shifted from the position P1 to the position P2.Meanwhile, the size of the formed image decreases, and the floating realimage shrinks.

It should appreciated that, the actuator 270 may also be used to movethe projection lens set 220 to achieve the effects of altering the sizeand position of the floating real image 260. As shown in FIG. 7B, themovement of the projection lens set 220 may be along the movementdirection M1, the movement direction M2, or the rotation direction M3.As shown in FIG. 7B, when the position of the projection lens set 220moves from the position P1 to the position P2, the corresponding imagelocation of the floating real image 260 is also shifted from theposition P1 to the position P2. Meanwhile, the magnifying power of theformed image is less than 1, and the floating real image shrinks. Forease of description, a single light path is used in the embodimentsillustrated in FIGS. 7A and 7B. The same principles apply when a displayapparatus has a plurality of light paths therein, and therefore furtherelaboration thereof is omitted.

FIG. 7C is a schematic view illustrating an adjustment of a floatingreal image location according to a user position in a display apparatusaccording to an embodiment of the disclosure. As shown in FIG. 7C, whena depth of the fingers of the user 10 touching the floating real image260 changes from position P1 to position P2, the depth detecting module240 detects the position variation of the fingers of the user 10, andfeeds a movement message back to the control unit 250 (depicted in FIGS.1 and 11). The control unit 250 transmits the movement message to theimage generator 210, so the image generator 210 corresponding moves fromposition P1 to position P2. Accordingly, the image location of thecorresponding floating real image 260 can be moved from the originalposition P1 to the position P2. Moreover, the depth detecting module 240may also be used to detect a state of the position of the user 10, suchas detecting a type of body language variation of the user 10, ordetecting a change in an object (e.g. a stylus) used by the user 10,although the disclosure is not limited thereto.

Using the display apparatuses shown in FIGS. 2 and 4 as examples, theembodiments of each display apparatus for rendering stereoscopic imagesare described.

FIGS. 8A and 8B are respective schematic views illustrating a userwearing a pair of stereoscopic glasses to view the display apparatushaving the projection lens set depicted in FIG. 2. As shown in FIG. 8A,in a display apparatus 300 of the present embodiment, the imagegenerator 210 is a display panel, for example. Moreover, a pair ofstereoscopic glasses 280 is, for example, a pair of shutter glasses 282having a scanning frequency. It should be noted that, when a switchingrate of the shutter glasses 282 is synchronized with the scanningfrequency of the image generator 210, the user 10 can view the virtualstereoscopic floating real image 260 displayed by a single display panelthrough the shutter glasses 282. For example, a display frequency of thedisplay panel is 120 Hz and the frequency of the switching rate of theshutter glasses 282 is 60 Hz. In other words, the display panelalternately displays 1/120 seconds of a left eye image 212L and 1/120seconds of a right eye image 212R. Moreover, the left and right lensesof the shutter glasses 282 respectively switch on and offcorrespondingly at 1/60 seconds, and accordingly the user 10 can viewthe stereoscopic floating real image 260 through the shutter glasses282. Furthermore, the floating real image 260 with stereoscopic imagingformed accordingly may also be constituted by a plurality ofsub-floating real images 260 a located on the same plane, or bysub-floating real images 260 a located on different same planes, and thedisclosure is not limited thereto. In other words, the display apparatus300 depicted in FIG. 8A renders the stereoscopic imaging effect for thefloating real image 260 by timing switching, and thus the resolution ofthe image can be maintained.

Another embodiment is shown in FIG. 8B. In a display apparatus 400 ofthe present embodiment, the scanning frequency of the image generator210 may be 60 Hz, and the stereoscopic glasses 280 is, for example, apair of polarized glasses 284 having two polarized lenses 284R and 284Lof different polarizing directions. For example, a right eye polarizedlens 284R has a perpendicular polarizing direction p, and a left eyepolarized lens 284L has a horizontal polarizing direction s. The image212 displayed by the display panel includes a right eye image 212R withthe perpendicular polarizing direction p and a left eye image 212L withthe horizontal polarizing direction s. Therefore, when the user 10 wearsthe polarized glasses 284, the user 10 can view the virtual stereoscopicfloating real image 260 displayed by a single display panel. Likewise,the floating real image 260 with stereoscopic imaging formed accordinglymay also be constituted by a plurality of sub-floating real images 260 alocated on the same plane, or by sub-floating real images 260 a locatedon different same planes, and the disclosure is not limited thereto. Inother words, since the display apparatus 400 depicted in FIG. 8B rendersthe stereoscopic imaging effect for the floating real image 260 byspatial combination, therefore, the display frequency of the displaypanel does not need to be accelerated, thereby simplifying circuitcontrol.

FIGS. 9A and 9B are respective schematic views illustrating a userwearing a pair of stereoscopic glasses to view the display apparatushaving the projection lens set depicted in FIG. 4. Referring to FIG. 9A,in a display apparatus 500 of the present embodiment, the imagegenerator 210 are two display panels, for example. Moreover, thestereoscopic glasses 280 is, for example, a pair of shutter glasses 282having a scanning frequency. In particular, when a switching rate of theshutter glasses 282 is synchronized with the scanning frequency of theimage generator 210, the user 10 can view the virtual stereoscopicfloating real image 260 displayed by the first image generator 210A andthe second image generator 210B through the shutter glasses 282. Forexample, the display frequency of the first image generator 210A and thesecond image generator 210B are 60 Hz, for example, and the frequency ofthe switching rate of the shutter glasses 282 is 60 Hz. In other words,the first image generator 210A may display a left eye image 212L every1/60 seconds, and the second image generator 210B may display a righteye image 212R every 1/60 seconds. Moreover, the left and right lensesof the shutter glasses 282 respectively switch on and offcorrespondingly at 1/60 seconds. Likewise, the floating real image 260with stereoscopic imaging formed accordingly may also be constituted bya plurality of sub-floating real images 260 a located on the same plane,or by sub-floating real images 260 a located on different same planesdepending on the display effect, and the disclosure is not limitedthereto. Since the display apparatus 500 depicted in FIG. 9A renders thestereoscopic imaging effect for the floating real image 260 by using twoimage generators 210, therefore, not only is the resolution of the image212 maintained, but the display frequency of the display panel also doesnot need to be accelerated, thereby simplifying circuit control.

Moreover, as shown in FIG. 9B, in a display apparatus 600 of the presentembodiment, the image generator 210 having two display panels is similarto FIG. 9A, for example. The stereoscopic glasses 280 of the presentembodiment is similar to the polarized glasses 284 depicted in FIG. 8B.The right eye polarized lens 284R has the perpendicular polarizingdirection p, and the left eye polarized lens 284L has the horizontalpolarizing direction s, for example. The first image generator 210A ofthe present embodiment displays the left eye image 212L having thehorizontal polarizing direction s, for example, and the second imagegenerator 210B displays the right eye image 212R having theperpendicular polarizing direction p. Therefore, when the user 10 wearsthe polarized glasses 284, the user 10 can view the virtual stereoscopicfloating real image 260 displayed by two display panels. Likewise, thefloating real image 260 with stereoscopic imaging formed accordingly mayalso be constituted by a plurality of sub-floating real images 260 alocated on the same plane, or by sub-floating real images 260 a locatedon different same planes, and the disclosure is not limited thereto. Inother words, since the display apparatus 600 depicted in FIG. 9B rendersthe stereoscopic imaging effect for the floating real image 260 by usingtwo image generators 210, therefore, not only is the resolution of theimage maintained, but the display frequency of the display panel alsodoes not need to be accelerated, thereby simplifying circuit control.

It should be noted that, in practical applications, the displayapparatus in the disclosure can rapidly move the image generator or theprojection lens set. Moreover, in conjunction with synchronized displayby the image generator, the visual retention characteristic of humanvision can be exploited to achieve a viewing effect of multiple layersof stacking images, and the stereoscopic floating real image generatedincludes a floating real image by binocular parallax, a floating realimage by motion parallax, or a combination of the two. It should beappreciated that, in practical applications, since the image locationsare not the same, the image size also shrinks or expands due to theobject-image relationship. On the other hand, when the floating realimage becomes distorted because of the restriction from the projectionlens set, front-end image processing can be performed in conjunctionwith the display portion to achieve the most preferable display effect.Moreover, when the display apparatus is an auto-stereoscopic displayapparatus, the related design parameters of the image generator (displaypanel) can be corrected by altering the object distance to adjust thelocation and the size of the floating real image, such that the user canview the most preferable stereoscopic effect. Specifically, by adjustingthe optical elements in the projection lens set of the displayapparatus, such as by changing a parallax barrier into a liquid crystalparallax barrier, altering the period of the parallax barrier, or byusing the parallax barrier to adjust the distance from the barrier tothe display pixels so as to achieve the needed stereoscopic effect, theloss of the stereoscopic effect of the floating real image from thechanging positions of the image generator can be prevented. Referenceregarding these techniques may be directed to the co-pending U.S. PatentApplication No. 61528766, Method for Autostereoscopic Display.

To be specific, FIGS. 10A and 10B are schematic views illustrating adisplay apparatus using auto-stereoscopic 3D display panels to replaceconventional 2D planar display panels according to an embodiment of thedisclosure. Referring to FIG. 10A, an auto-stereoscopic 3D display panel210′ forms a stereoscopic 3D floating real image 260′ at an image sidethrough the projection lens set 220. Meanwhile, an original viewing zoneZA having an optimal viewing position of the auto-stereoscopic 3Ddisplay panel 210′ forms, at an image side, a viewing zone ZB having anoptimal viewing position of the stereoscopic 3D floating real image 260′formed through the projection lens set 220 and is floating in air. Asshown in FIG. 10A, the display apparatus has two object-imagerelationships, respectively the object-image relationship of theauto-stereoscopic 3D display panel 210′ and the stereoscopic 3D floatingreal image 260′, and the object-image relationship of the viewing zoneZA having the optimal viewing position of the auto-stereoscopic 3Ddisplay panel 210′ and the viewing zone ZB having the optimal viewingposition of the stereoscopic 3D floating real image 260′. These twoobject-image relationships are related to the image locations andmagnifying powers thereof and should be considered concurrently.Referring to FIGS. 10A and 10B, the depth detecting module 240 candetect the position of the user 10 or the position and the size thestereoscopic 3D floating real image 260′, and accordingly feeds theinformation back to the auto-stereoscopic 3D display panel 210′ and theprojection lens set 220. Since the magnifying power of the projectionlens set 220 is M, the size of the image projected by theauto-stereoscopic 3D display panel 210′ in the viewing zone ZA is E/M,in which E is image size locate in the viewing zone ZB. Moreover, thesize of subpixels (SS) of the image provided by the auto-stereoscopic 3Ddisplay panel 210′, the distance T between the auto-stereoscopic 3Ddisplay panel 210′ to the view ZA, and the size E/M of the imageprovided by the auto-stereoscopic 3D display panel 210′ satisfy afollowing formula:

${\left( {N \times {SS}} \right)\text{/}\left( {\frac{E}{M}\text{/}\Delta \; N} \right)} = {\frac{t}{n\; 1}\text{/}\frac{T}{n\; 2}}$${{N \times {SS}\text{/}P} = {\left( {\frac{T}{n\; 2} + \frac{t}{n\; 1}} \right)\text{/}\frac{T}{n\; 2}}},$

in which n1 and n2 are respective refractive indices between theparallax barrier and the display panel and between the parallax barrierand the viewer, n1 is 1.523 for glass, and n2 is 1 for air, for example.Moreover, P is a period of the parallax barrier, t is the distancebetween the parallax barrier and the display panel, N is a number ofviewing zones of the stereoscopic display panels, and ΔN is a viewingzone difference seen by the viewer. For example, if the left and righteyes respectively sees viewing zones 1 and 3, then ΔN is 2. Therefore,according to the position of the user 10 or the position and size of thestereoscopic 3D floating real image 260′ detected by the depth detectingmodule, the display apparatus in the disclosure can correspondinglyadjust the magnifying power and the image location of the projectionlens set.

FIG. 11 is a schematic view illustrating a framework of a displayapparatus according to an embodiment of the disclosure. Referring toFIG. 11, in the present embodiment, a device generating the first image212A is a display panel, for example, and a device generating the secondimage 212B is a physical keypad. By using the afore-described projectionlens set 220, the keypad may be projected in front of the user 10 so asto generate a floating real image 260 of a 3D keypad with depthperception. When the user 10 is at a suitable viewing position, thefloating real image 260 is, for example, floating 20 cm in front of theprojection lens set 220, and the user 10 can view the floating realimage 260 at a position that is 70 cm in front of the projection lensset 220. Accordingly, the distance from the user 10 to the floating realimage 260 is 50 cm, which is a comfortable distance for the arms of mostpeople to touch an object. In one usage scenario, when the user 10touches any key, the depth detecting module 240 may detect a keylocation touched by the fingers of the user 10, and feeds a touchmessage back to the control unit 250. A corresponding message (e.g., apreset image or voice feedback message) is sent to the user 10, andaccordingly an interactive effect is achieved.

Moreover, the display apparatus in the disclosure may utilize theafore-described active depth detecting module 240 in order to have thedisplay apparatus respond to the user. In other words, the displayapparatus in the disclosure not only has the image variation depicted inFIGS. 10A and 10B, but furthermore, the active depth detecting module240 can be used to feedback control the entire system of the displayapparatus, thereby achieving the interactive function. Furtherelaboration of the depth detecting module 240 is provided below.

In another embodiment of the disclosure, an active depth detectingmodule 240 is included. In conjunction with the afore-described opticaldesign, the user can be provided with free-space real images forhuman-machine interaction, so that the user can touch the imagesfloating in natural space. Moreover, by the feedback of the detectedfinger depth variation, the corresponding image content can be generatedto achieve the interactive effect.

Reference for an active depth detecting module that may be applied inthe disclosure can be directed towards the co-pending U.S. PatentApplication No. 61475648, Apparatus and Method for Depth ImageCapturing. By projecting specific patterns on the detection object usingan active light source, an image depth information of the detectionobject can be calculated by a real and virtual image comparisontechnique. The active light source is formed by a light source and adesigned diffractive optical lens set, capable of generating irregularlydistributed bright spot images, controlling the size of the incidentbeam, and adjusting a distribution density of the bright spot images.The principles for calculating the depth images is based on imagecomparison techniques. Besides simultaneously obtaining projectionpattern images from two sets of synchronized video cameras, anembodiment of the disclosure further uses the projection device as avirtual video camera, so as to respectively calculate the correspondingspatial relationship of each video camera and the projection device.Thereafter, the disparity images are utilized for mutual verification,thereby enhancing an accuracy thereof and compensating for an imageshielding issue.

Referring to FIG. 11, an embodiment of the disclosure projections animage having a specific content in free space by using a combination ofthe afore-described optical framework and image display techniques. Theimage displayed includes 2D and 3D images as described earlier. Forexample, a 3D keypad with depth perception may be displayed in space.When the user 10 is at a suitable viewing position, the afore-describedoptical design floats the image 20 cm in front of the projection lensset 220, and the viewer can view the image by standing 70 cm in front ofthe projection lens set 220. Accordingly, the distance from the user 10to the image is 50 cm, which is a comfortable distance for the arms ofmost people to touch an object. When the user 10 touches a key (thesecond sub-floating real image), the active depth detecting module 240can detect where the fingers lightly pressed the key. Since the user 10has only touched the key but has not actually done a press down action,a simulated key press effect cannot be achieved. Therefore, the activedepth detecting module may detect the slight finger depth variation andfeedback to the control unit 250, so as to receive a correspondingresponse message including an image or voice feedback message. Theentire framework may be as shown in FIG. 11.

The active depth detecting module in the disclosure may be used in anyafore-described arbitrary optical frameworks as well as on the imageside. In conjunction with the generation of the display image and thefeedback message, the display apparatus may be applied in many publicplaces, such as in automatic teller machines (ATMs), public phones, ornavigation systems. Furthermore, in order for the simulated effects toappear more realistic, a force feedback device may be added to enhance asense of reality for touching the floating real images.

Besides referring to the co-pending U.S. Patent Application No.61475648, Apparatus and Method for Depth Image Capturing for the activedepth detecting module projecting specific patterns on the detectionobject, a light source of a specific wavelength may also be projected.The depth is detected by the reflected signals, and an infrared lightsource is typically used to prevent interference from the externalvisible light. In addition to the active depth detecting module, apassive depth detecting module may also be adopted, such as dual videocameras for image capture that obtains depth information by an imagecomparison technique.

Besides detecting the finger depth variation, the depth detecting modulein the disclosure may also be used to detect various types of bodylanguage changes to the user, or a change in an object, such as a stylusor the like.

Moreover, the display apparatus may further include an interactivemodule formed by a depth detecting module and a force feedback system,in which the force feedback system and the depth detecting module areconnected. The depth detecting module may be an active depth detectingmodule or a passive depth detecting module. To be specific, in oneembodiment, the active depth detecting module may use one or more lightsensing elements to calculate an image depth information of a detectionobject by a real and virtual image comparison technique, in whichspecific patterns are projected on the detection object using an activelight source. In another embodiment, a light sensing element is used tocalculate the image depth information of the detection object by atriangulation distance measuring technique, in which a laser may beactively emitted on the detection object. Alternatively, by using anultrasonic receiver, the active depth detecting module may alsocalculate the image depth information of the detection object by around-trip time of an ultrasound wave actively emitted on the detectionobject. Moreover, the depth detecting module is suitable for detectingspatial positions of the limbs of the user or an operating object, so asto perform interactive control with floating real images of differentdepth positions. The force feedback system feeds a tactile sensation oftouching the floating real image back to the user, and accordingly theuser and the floating real images can interact with each other.

In view of the foregoing, by the emitted beam from the projection lensset satisfying a specific relationship, the display apparatus in thedisclosure can generate a floating real image between the projectionlens set and the user. Moreover, by using the depth detecting module todetect the user position, and the control unit electrically connected tothe image generator, the projection lens set, and the depth detectingmodule, the image generator and the projection lens set can adjust theposition of the floating real image according to the user position. Insome embodiments, the floating real image is an auto-stereoscopic image,or a stereoscopic floating real image viewable by a pair of stereoscopicglasses. Accordingly, the display apparatus in the disclosure canprovide the user a realistic interactive experience that is true tolife.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the structure of thedisclosed embodiments without departing from the scope or spirit of thedisclosure. In view of the foregoing, it is intended that the disclosurecover modifications and variations of this disclosure provided they fallwithin the scope of the following claims and their equivalents.

1. A display apparatus suitable for viewing by a user, the displayapparatus comprising: at least an image generator displaying at least animage; a projection lens set located between the image generator and theuser, the image projected by the projection lens set and generating afloating real image between the projection lens set and the user,wherein each beam forming the floating real image has a light-cone angleθ, each beam has a chief ray and a plurality of marginal rays, eachmarginal ray and the corresponding chief ray has an included angle α,and the light-cone angle θ=2α; a depth detecting module detecting theposition of the user, the image generator and the projection lens setadjusting the position of the floating real image according to theposition of the user, wherein the size of the floating real image is L,the distance between two eyes of the user is W, the distance between theuser and the floating real image is D, and the light-cone angle θsatisfies a formula:${\theta \geq {\tan^{- 1}\left( \frac{L + W}{D} \right)}};$ and acontrol unit electrically connected to the image generator, theprojection lens set, and the depth detecting module.
 2. The displayapparatus as claimed in claim 1, wherein the control unit controls amovement of the image generator according to the position of the userdetected by the depth detecting module, so as to adjust a relativepositions of the image generator and the projection lens set, theposition of the floating real image, and the size of the floating realimage.
 3. The display apparatus as claimed in claim 1, wherein thedisplay apparatus comprises one image generator, and the projection lensset comprises two lens sets disposed on a projection path of the image.4. The display apparatus as claimed in claim 1, wherein the displayapparatus comprises one image generator, and the projection lens setcomprises: a reflector located on a projection path of the image; afirst lens set located on the projection path of the image and formed byat least a lens, and a total focal length of the first lens set is apositive value; and a second lens set located on the projection path ofthe image and between the reflector and the user, the second lens setformed by at least a lens, and a total focal length of the second lensset is a positive value.
 5. The display apparatus as claimed in claim 1,wherein the image generator comprises a first image generator and asecond image generator, the first image generator displaying a firstimage, and the second image generator displaying a second image, theprojection lens set comprising: a beam combiner located on a projectionpath of the first image and the second image, and the beam combinerreflects the first image and transmits the second image; a first lensset located on a projection path of the first image and between thefirst image generator and the beam combiner, the first lens set formedby at least a lens; a second lens set located on a projection path ofthe second image and between the second image generator and the beamcombiner, the second lens set formed by at least a lens; and a thirdlens set located on the projection path of the first image and thesecond image and between the beam combiner and the user, the third lensset formed by at least a lens.
 6. The display apparatus as claimed inclaim 1, wherein the image generator comprises a first image generator,a second image generator, and a third image generator, the first imagegenerator displaying a first image, the second image generatordisplaying a second image, and the third image generator displaying athird image, the projection lens set comprising: a first beam combinerlocated on a projection path of the first image, second image, and thethird image, the first beam combiner reflecting the first image and thethird image and transmitting the second image; a second beam combinerlocated on a projection path of the first image and the third image, thesecond beam combiner reflecting the third image and transmitting thefirst image; a first lens set located on the projection path of thefirst image and the third image and between the second beam combiner andthe first beam combiner, the first lens set formed by at least a lens; asecond lens set located on a projection path of the second image andbetween the second image generator and the first beam combiner, thesecond lens set formed by at least a lens; a third lens set located onthe projection path of the first image, the second image, and the thirdimage, and located between the first beam combiner and the user, thethird lens set formed by at least a lens; and a fourth lens set locatedon a projection path of the third image and between the third imagegenerator and the second beam combiner, the fourth lens set formed by atleast a lens.
 7. The display apparatus as claimed in claim 1, whereinthe display apparatus comprises more than one image generators, and thefloating real image comprises a plurality of sub-floating real imageslocated on different planes.
 8. The display apparatus as claimed inclaim 1, wherein the display apparatus comprises more than one imagegenerators, and the floating real image comprises a plurality ofsub-floating real images located on a same plane.
 9. The displayapparatus as claimed in claim 1, wherein the display apparatus comprisesat least one image generator, and the floating real image comprises atleast a stereoscopic floating real image, wherein the stereoscopicfloating real image comprises a floating real image of binocularparallax, a floating real image of motion parallax, or a combination ofthe two.
 10. The display apparatus as claimed in claim 1, wherein thesize of the floating real image is greater than or less than the size ofthe image.
 11. The display apparatus as claimed in claim 1, wherein thesize of the floating real image is equal to the size of the image. 12.The display apparatus as claimed in claim 1, further comprising a pairof stereoscopic glasses, wherein the floating real image viewed by theuser through the stereoscopic glasses is a stereoscopic image.
 13. Thedisplay apparatus as claimed in claim 12, wherein the pair ofstereoscopic glasses is a pair of shutter glasses, the image generatorhaving a scanning frequency, and a switching frequency of the pair ofshutter glasses is synchronized with the scanning frequency of the imagegenerator.
 14. The display apparatus as claimed in claim 12, wherein thepair of stereoscopic glasses is a pair of polarized glasses, thepolarized glasses having two polarized lenses with different polarizingdirections.
 15. The display apparatus as claimed in claim 1, wherein theimage generator comprises a display panel, a light emitting device, oran object being illuminated by light.
 16. The display apparatus asclaimed in claim 1, wherein the display apparatus further comprises aninteractive module, comprising: the depth detecting module; and a forcefeedback system connected to the depth detecting module.
 17. The displayapparatus as claimed in claim 16, wherein the depth detecting module isan active depth detecting module.
 18. The display apparatus as claimedin claim 16, wherein the depth detecting module is a passive depthdetecting module.
 19. The display apparatus as claimed in claim 17,wherein the active depth detecting module uses one or more light sensingelements to calculate an image depth information of a detection objectby a real and virtual image comparison technique, wherein a plurality ofspecific patterns are projected on the detection object by using anactive light source.
 20. The display apparatus as claimed in claim 17,wherein the active depth detecting module uses a light sensing elementto calculate an image depth information of a detection object by atriangulation distance measuring technique, wherein a laser is activelyemitted on the detection object.
 21. The display apparatus as claimed inclaim 17, wherein the active depth detecting module uses an ultrasonicreceiver to calculate an image depth information of a detection objectby a round-trip time of an ultrasound wave actively emitted on thedetection object.
 22. The display apparatus as claimed in claim 17,wherein the depth detecting module is suitable for detecting a spatialposition of the limbs of the user or an operating object, so as toperform interactive control with floating real images of different depthpositions.
 23. The display apparatus as claimed in claim 17, wherein theforce feedback system feeds a tactile sensation of touching the floatingreal image back to the user.